Abstract
A processed gene potentially coding for a sarcomeric actin has been identified in Xenopus laevis and in the more primitive species X. tropicalis. The peptides encoded in these two species differ by two out of 377 amino acid residues. On the basis of the amino acid substitutions, the encoded peptide was identified as an alpha-skeletal actin in X. laevis and as an alpha-cardiac actin in X. tropicalis. Northern blot analysis and S1 mapping experiments suggest that in X. tropicalis the gene is expressed in embryos and adult heart. In X. laevis, transcripts homologous to this gene were found in embryos and in adult tissues, but predominantly in skeletal muscle rather than in heart.